650 research outputs found
Government ownership and the cost of debt : evidence from government investments in publicly traded firms
Contrary to public perceptions and despite the worldwide success of state
privatizations, over the past decade governments have acquired more assets
through stock purchases (US 765 billion). In fact, governments and stateowned
entities have been such active stock-market investors that they now own
approximately one-fifth of global stock-market capitalization
Influence of exogenous urea on photosynthetic pigments, 14CO2 uptake, and urease activity in Elodea densa-environmental implications
This paper analyzes the effect of exogenous urea in increased concentration gradient (0, 100, 500 and 1,000 mg L-1) on photosynthetic pigments (measured spectrophotometrically), uptake of 14CO2 (using radioisotope), and urease activity (by measuring ammonia with Nessler's reagent) in leaves of Elodea densa Planch. We have observed that low concentration of urea (100 mg L-1) stimulates the accumulation of photosynthetic pigments and intensifies photosynthesis in E. densa, whereas high concentration (1,000 mg L-1) suppresses these processes. Urease activity increased by approximately 2.7 and 8 fold when exogenous urea concentrations were 100 and 500 mg L-1, respectively. However, exogenous urea in high concentration (1,000 mg L-1) decreased urease activity by 1.5 fold compared to the control. The necessity of mitigating urea and other nitrogen-containing compounds (NH3 from urea) in water bodies has been discussed with emphasis on the potential for phytoremediation of urea using common water weed viz. E. densa. © 2013 Springer-Verlag Berlin Heidelberg
Effect of nitrogenous bases on the thermal stability of jet fuels
Fuels from naphthenic petroleums were evaluated, and it was found that they had more N bases than those paraffinic ones (0.00024 and 0.000009% N, respectively). The removal of the N bases improved significantly the thermal stability and reduced the residue formation during oxidation of the fuel. The improvement depended on both content and composition of the bases. Thus, fuels with similar content of N bases (0.00058% N) and thermal stability had oxidation residues of 17.5 and 5.6 and sol. gum of 13 and 1.5 mg/100 ml, before and after removing the N bases, respectively
Leaf Mesophyll Structure and Photosynthetic Activity in Calla palustris L. from Natural Habitats with Different Level of Technogenic Pollution
A study of leaf structure and CO2 assimilation rate was conducted on the emergent plant Calla palustris L. from natural habitats with different levels of technogenic pollution (the Sak-Elga River, upstream and downstream of the Karabash copper smelter, Chelyabinsk region, Russia). It was found that both chlorophyll a content andthe rate of CO2 assimilation decreased twofold in plants from the downstream site. No significant changes were observed in leaf mesophyll structure and the volume of aerenchyma in the leaf. It was shown that in plants from strongly contaminated site, the decrease in spongy mesophyll cell volume was compensated by the increase in their number, whereas the decrease in the number of chloroplasts per cell was accompanied by a growth in volume. It is concluded that the changes in the numerical and dimensional characteristics of mesophyll cells and chloroplasts provide for the viability of C. palustris under prolonged technogenic impact and demonstrate the plasticity of the photosynthetic apparatus.
Keywords: emergent plant, heavy metals, adaptation, leaf structure, CO2 uptak
Antiproliferative activity of a new derivative from the class of N-glycoside of indolo [2,3-a] pyrrolo [3,4-c] carbazoles
The aim of the study was to evaluate an antiproliferative activity of a new, Russian derivative of N-glycoside substituted indolocarbazole 6-amino-12-(α-L-arabinopyranosyl)indolo [2,3-a] pyrrolo [3,4-c] carbazole-5,7-dione (LCS-1208) on models of transplantable tumors of mice and on human tumors in Balb/c nude mic
Government ownership and the cost of debt : evidence from government investments in publicly traded firms
Contrary to public perceptions and despite the worldwide success of state
privatizations, over the past decade governments have acquired more assets
through stock purchases (US 765 billion). In fact, governments and stateowned
entities have been such active stock-market investors that they now own
approximately one-fifth of global stock-market capitalization
Diagnostic Criteria for Macular Edema Associated with Venous Occlusions
Background. Macular edema is considered as a risk factor for a significant decrease in the visual acuity and quality of life of the patient, regardless of its cause. The search for the causes of macular edema in some cases should include an interdisciplinary approach and laboratory studies to correctly determine its etiology and management tactics for such patients. Therefore, the differentiation of the etiology and pathogenesis of macular edema at the stage of diagnosis determines the possibility of preserving not only visual functions, but in some cases the patient's life.Aim: to present clinical cases of macular edema associated with central retinal vein thrombosis of various etiologies. Materials and methods. A prospective study of individual patients with macular edema associated with thrombosis of central retinal vein or its branches was conducted in real clinical practice. All patients underwent a standard ophthalmological examination, as well as optical coherence tomography, and a patient with suspected macroglobulinemia underwent a biochemical blood test.Results. In the first clinical case, macular edema was associated with an exudative form of retinal arterial macroaneurysm. The patient underwent direct laser coagulation of retinal arterial macroaneurysm. 6 months after direct laser coagulation of macroaneurysm, the best corrected visual acuity of the left eye was 1.0. The fundus - macroaneurysm, retinal edema, solid exudates are not ophthalmoscopic. In the second clinical case, macular edema, thrombosis of central retinal vein is associated with Waldenstrom disease. Follow-up and treatment of the underlying disease by a hematologist were recommended.Conclusion. Thus, macular edema proceeding against the background of central retinal vein thrombosis and its branches, having atypical symptoms in the form of ring-shaped deposition of hard exudates, exudative retinal detachment, the presence of a bilateral process, as well as resistance to anti-VEGF therapy require a careful collection of the patient's medical history and the presence of other ophthalmic vascular pathology
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